Considering a multi mode User Entity UE capable of communicating with two or more different types of radio access networks, for example GSM (Global System for Mobile communication) and UMTS (Universal Mobile Telecommunication Service), in IDLE state, the dual mode GSM/UMTS UE performs network selection as follows:
1. Try to select the last registered PLMN (Public Land Mobile Network),
2. Try to select the home PLMN,
3. Try to select a PLMN specified in the (U) SIM ((UMTS) Subscriber Identity Module) PLMN selector list,
4. Try to select any other PLMN.
After that, the Radio Access Network RAN (e.g. GSM RAN or UMTS RAN) and a cell are selected based on the signal strength. In other words, there is no preference of either RAN type over the other. After the UE has camped to a particular cell, it performs a registration to the PLMN. Whenever the user requests service from the network, it is initiated via the camped cell in the selected RAN.
When a UE is in ACTIVE state, e.g. the user has an ongoing call, the radio network controller in the respective RAN and the Core Network CN take care of the user's mobility by means of soft and hard handovers. In current mobile communication networks, a handover decision algorithm is located in a radio network controller of the respective radio access network, and it is not standardized in 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute), i.e. it is proprietary. The UE has no control over the type of radio access network via which the service is provided.
Moreover, current 3GPP and ETSI specifications do not provide any tools for an operator operating a GSM/UMTS network, for example, which enable the usage of either of them over the other.
However, operators have indicated that they need means to control what type of radio access network users are using. Control over the used radio access system type becomes even more necessary, when new radio access systems are introduced to current wireless communication systems, for example BRAN (Broadband Radio Access Networks) and GERAN, and integration with other access types, e.g. WLAN (Wireless Local Area Network), becomes reality.
Up to now, merely a mechanism has been presented, which is a parameter in a Channel Type Information Element in Base Station System Management Application Part protocol and can be used to hand over a connection from GSM to UMTS.